---
id: CVE-2025-62504
title: Envoy is an open source edge and service proxy
summary: >-
  Envoy is an open source edge and service proxy. Envoy versions earlier than
  1.36.2, 1.35.6, 1.34.10, and 1.33.12 contain a use-after-free vulnerability in
  the Lua filter. When a Lua script executing in the response phase rewrites a
  respo…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-416
vendor: envoyproxy
product: envoy
affected:
  - envoy < 1.33.12
  - 'envoy >= 1.34.0, < 1.34.10'
  - 'envoy >= 1.35.0, < 1.35.6'
  - 'envoy >= 1.36.0, < 1.36.2'
patched:
  - envoy 1.36.2
published: '2025-10-16'
updated: '2026-10-09'
sourceUpdated: '2026-10-09T10:10:00.193'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-62504'
references:
  - url: >-
      https://github.com/envoyproxy/envoy/security/advisories/GHSA-gcxr-6vrp-wff3
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.0042
epssPercentile: 0.34322
ingestedAt: '2026-10-09T12:53:29.107Z'
---

## Overview

Envoy is an open source edge and service proxy. Envoy versions earlier than 1.36.2, 1.35.6, 1.34.10, and 1.33.12 contain a use-after-free vulnerability in the Lua filter. When a Lua script executing in the response phase rewrites a response body so that its size exceeds the configured per_connection_buffer_limit_bytes (default 1MB), Envoy generates a local reply whose headers override the original response headers, leaving dangling references and causing a crash. This results in denial of service. Updating to versions 1.36.2, 1.35.6, 1.34.10, or 1.33.12 fixes the issue. Increasing per_connection_buffer_limit_bytes (and for HTTP/2 the initial_stream_window_size) or increasing per_request_buffer_limit_bytes / request_body_buffer_limit can reduce the likelihood of triggering the condition but does not correct the underlying memory safety flaw.

## Affected

- `envoy < 1.33.12`
- `envoy >= 1.34.0, < 1.34.10`
- `envoy >= 1.35.0, < 1.35.6`
- `envoy >= 1.36.0, < 1.36.2`

## Remediation

Upgrade past the affected range:

- `envoy 1.36.2`